Panel and Use of Such a Panel in a Device for Cleaning Gases by Removing Impurities Therefrom

ABSTRACT

The invention relates to a panel, comprising: two plates of substantially equal dimensions positioned on each other; which plates are connected medium-tightly to each other along their peripheral zones; which plates enclose a cavity; a feed for feeding a liquid, in particular water, into the cavity; and openings close to and along a peripheral edge of the panel for flow of the liquid out of the cavity during operation such that during operation the openings are situated close to the upper peripheral edge of the panel, wherein the liquid flows downward over at least one outer surface of the panel.

BACKGROUND OF THE INVENTION

The invention relates to a panel, particularly for use in a device forcleaning gases by removing impurities therefrom, a method formanufacturing such a panel, a method for cleaning such a panel and adevice and method for cleaning gases. Cleaning of gases is particularlyunderstood to mean at least the removal of impurities from gases.

The impurities may comprise solid constituents, fluid constituentsand/or gaseous constituents.

A known panel is used for instance in a device for cleaning flue gases,wherein the device comprises a plurality of panels disposed verticallyat a distance from each other, wherein water flows downward over bothsides of the panels for the purpose of removing impurities from thegases which have accumulated on the sides. For the purpose of causingthe water to flow over the sides the known device is provided with ahorizontal header which is filled with water and which is provided onits underside with a number of fine holes, these holes generating a flowof water to a smooth tube which in turn delivers the downward flowingwater to both sides of a panel. Drawbacks of the known device are thatthe positioning of the header and the smooth tube above the panelrequires precision, and that the device is expensive, susceptible tobreakdown, difficult to maintain and replacement of parts is awkward.

SUMMARY OF THE INVENTION

It is an object of the invention to obviate the above stated drawbacks.For this purpose the panel according to the invention comprises:

two plates of substantially equal dimensions positioned on each other;

which plates are connected medium-tightly to each other along theirperipheral zones;

which plates enclose a cavity;

a feed for feeding a liquid, in particular water, into the cavity; and

openings close to and along a peripheral edge of the panel for flow ofthe liquid out of the cavity during operation such that during operationthe openings are situated close to the upper peripheral edge of thepanel, wherein the liquid flows downward over at least one outer surfaceof the panel.

The plates may consist of any suitable material, e.g. a metal, such asaluminum, steel, particularly stainless steel or carbon-steel, or asynthetic resin, if necessary fiber-reinforced, e.g. a glass-fiberreinforced epoxy resin.

An advantage of the panel according to the invention is that the cavityin the panel can be used to press water supplied via the feed, which ispreferably situated close to the lower peripheral edge of the panel,upward from the underside such that the water flows through the openingsclose to the upper peripheral edge and downward over the relevant outersurface of the panel. When the panel is used in a device for cleaninggases, the header and the smooth tube are hereby unnecessary, wherebypossible problems with the positioning of the header and the smooth tubeabove a panel do not occur. Furthermore, material is hereby saved andinstallation and maintenance of the device are simplified.

The openings are preferably arranged in at least one of the two plates.This provides a practical advantage, since the openings can be arrangedin the plates in simple manner by means of drilling or laser cutting.The openings are preferably situated at a constant mutual distance,wherein the distance between an opening and the nearby peripheral edgeof the panel is the same for each opening. The openings are preferablysufficiently large to allow a substantially laminar flow of the liquidout of the openings during operation. An advantage hereof is that thewater may flow uniformly over the outer surfaces of the panel.

In a practical embodiment the panel according to the invention has thefeature that the feed is situated close to a second peripheral edge ofthe panel, which second peripheral edge extends opposite the peripheraledge close to which the openings are arranged.

The panel according to the invention is manufactured in simple mannerwith a method according to the invention, comprising the followingsteps, to be performed in suitable sequence, of:

(a) positioning two plates of substantially equal dimensions relative toeach other;

(b) connecting the two plates medium-tightly to each other along theirperipheral zones;

(c) arranging a feed in the panel;

(d) feeding an inflating medium under pressure via the feed such thatthe two plates, undergoing plastic deformation, move apart in the areabetween the peripheral seams, thereby creating a panel with a cavity;and

(e) arranging openings close to and along one peripheral edge of thepanel for flow of a liquid out of the cavity during operation.

The openings can be arranged in simple manner by means of drilling,laser cutting, or any other suitable method. This may take placeaccording to the invention after step (d), since otherwise the buildupof the pressure in the panel for the purpose of moving apart the plateswith plastic deformation is not practically possible, unless thepreviously arranged openings are, for the purpose of pressurizing thepanel, temporarily closed, e.g. by means of adhesive tape that isremoved after removing the internal pressure. According to this methodthe flat plates may be provided with the through-holes prior to weldingthem together and inflating them in order to arrive at a hollow panelaccording to the invention.

The method preferably comprises the step of

(f) locally connecting the two plates to each other prior to step (d) bymeans of a pattern of welded zones distributed regularly over thesurface, wherein in step (d) the two plates, undergoing plasticdeformation, move apart in areas between the welded zones.

Through the arrangement of such welded zones the panel at leastsubstantially retains its peripheral form and a more or less flat formduring the plastic deformation.

The method preferably comprises the step of

(g) exposing the two plates to a corona treatment, wherein greasepresent on the plates degrades such that the liquid flowing through theopenings during operation forms a thin film on at least one outersurface of the panel.

The panel according to the invention is easily cleaned with a methodaccording to the invention, comprising the step of

(h) placing the cavity into medium-throughflow connection with theenvironment via the feed for the purpose of discharging the liquidpresent in the cavity from the cavity via the feed such that anunderpressure is created in the cavity.

This method for cleaning the panel can be applied particularly when theopenings in the panel are blocked. Owing to the created underpressureair will be suctioned through the openings into the cavity, whereby theblockage is removed in simple manner from the openings.

The panel according to the invention is used particularly in a devicefor cleaning gases, which device comprises:

at least two panels according to the invention disposed vertically at amutual distance;

these panels being disposed such that the openings are situated close tothe upper peripheral edge of the panel;

at least one corona electrode arranged between adjacent panels for thepurpose of ionizing impurities present in the gases;

a voltage source connected between the or each corona electrode and eachpanel such that a voltage is applied between the or each coronaelectrode and each panel, whereby impurities present in the gases areionized;

which ionized impurities collect during operation on the surfaces of thepanels directed toward the gases;

which collected impurities are removed from the panels during operationby means of the liquid which flows downward out of the openings over thesurfaces of the panel directed toward the gases; and

a discharge for discharging the liquid with the collected impurities.

As described above, the header and the smooth tube as applied in theknown device are unnecessary, whereby possible problems with positioningof the header and the smooth tube above a panel do not occur. Accordingto the invention a reliable and/or inexpensive device is hereby providedfor cleaning gases, this device being simple to maintain and install.

The device according to the invention preferably comprises receivingmeans for receiving the liquid with the collected impurities, thesereceiving means being connected to the discharge.

The device preferably further comprises a housing in which at least thepanels and the corona electrode are accommodated.

The invention further relates to a method for cleaning gases, the methodcomprising the following steps, to be performed in suitable sequence,of:

(i) guiding the gases for cleaning between at least two panels accordingto any of the claims 1-5 disposed vertically at a mutual distance,wherein the panels are disposed such that the openings are situatedclose to the upper peripheral edge of the panel;

(j) exposing the gases for cleaning to corona discharge for the purposeof ionizing impurities present in the gases;

(k) collecting the impurities on the surfaces of the panels directedtoward the gases;

(l) feeding a liquid via the feed into the cavity for the purpose ofcausing the liquid to flow out of the cavity through the openings;

(m) removing the collected impurities from the panels by means of theliquid which flows downward out of the openings over the surfaces of thepanel directed toward the gases; and

(n) discharging the liquid with the collected impurities.

The liquid is preferably fed into the cavity under low pressure via thefeed in step (l), wherein the feed is situated close to the lowerperipheral edge of the panel, and wherein the method comprises the stepof

(o) pressing the liquid upward in the direction of the openings for thepurpose of causing the liquid to flow out of the cavity through theopenings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further elucidated with reference to figures shownin a drawing, wherein

FIG. 1 shows a perspective view of a panel according to the invention;

FIG. 2 shows a cross-section through the top part of the panel of FIG.1;

FIG. 3 shows a perspective view of a device for cleaning gases accordingto the invention;

FIG. 4 shows a perspective view of a panel according to the invention ina second embodiment; and

FIG. 5 shows a vertical cross-section according to the plane V-V of FIG.4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show a panel 1, in this specific embodiment comprising twostainless steel plates 2 of substantially equal dimensions and a feed 3.Plates 2 are connected to each other along their peripheral zones andenclose a cavity 7 which is in medium-throughflow connection with feed3. Close to one peripheral edge of panel 1 the plates 2 are providedwith openings 4, these openings 4 being in medium-throughflow connectionwith cavity 7. FIG. 1 shows that openings 4 are arranged in a straightrow parallel to the relevant peripheral edge, wherein the mutualdistance between each two successive openings 4 is constant.

During operation (see also FIG. 3) panels 1 are disposed vertically,wherein openings 4 are situated close to and along the upper peripheraledge of the panel. Feed 3 is situated during operation on the undersideof panel 1 and is used to supply water into cavity 7 at low pressure(order of magnitude of for instance several tenths bar), after which thewater in cavity 7 is pressed upward in the direction of openings 4. Thewater then flows out of cavity 7 through openings 4 and downward in thedirection 8 over outer surfaces 5 of panel 1 to the underside of panel1, where the water runs off panel 1 in direction 6. Openings 4 arepreferably sufficiently large to allow at least substantially laminarflow of the water out of openings 4.

Panel 1 can be any hollow panel through which liquid can flow, the panelbeing provided according to the invention with openings 4 close to andalong one peripheral edge. Panel 1 particularly comprises a so-calledpillow plate shown in FIGS. 4 and 5 which is per se known and ismanufactured according to the invention as follows.

Two plates 2 of substantially equal dimensions are first positioned oneach other, wherein a feed 3 is arranged between the two plates 2 suchthat feed 3 extends at least partially outside the two plates 2. The twoplates 2 are then connected medium-tightly to each other along the wholeperipheral zone 22, for instance by means of laser welding or seamwelding.

Plates 2 are connected locally to each other by means of a pattern, inthis case a so-called diamond pattern, of welded zones, in this casesubstantially circular zones 23 distributed regularly over the surface,in particular by laser welding. The welded zones can be arranged withany desired form, such as, though not exclusively, oval, circular orpolygonal. In this arbitrary embodiment the round laser welding zones alhave diameters of about 20-50 mm.

Via feed 3 water under pressure (order of magnitude for instance severalhundreds psi's) is then supplied such that the two plates 2 move apartwhile undergoing plastic deformation in the area between the peripheralseams and the welded zones, and cavity 7 is formed. In this embodimentfeed 3 is thus used to manufacture panel 1 as well as during use ofpanel 1.

It is noted that the above described steps can be performed in anysuitable sequence. The step described below is however preferablyperformed after the supply of the water under pressure. This stepcomprises of arranging openings 4 close to and along the relevantperipheral edge of panel 1.

If openings 4 are arranged prior to the supplying of the water underpressure, the buildup of the pressure in panel 1 for the purpose ofmoving apart plates 2 with plastic deformation would not be practicallypossible, unless the openings 4 are temporarily closed prior topressurizing the panel, e.g. by applying an adhesive tape over theopenings 4.

Openings 4 according to the invention can be arranged in any desiredmanner. Openings 4 are arranged in practical manner by drilling holes inthe two plates 2, or by laser cutting.

It is noted that, preferably before they are connected to each other,plates 2 undergo a corona treatment. Grease present on plates 2 herebydegrades, whereby the liquid flowing through openings 4 during operationforms a thin film on outer surfaces 5 of the panel. As an alternative,or in combination therewith, a coating with a micro-molecular ornano-material may be applied, with the same effect.

FIG. 3 shows a device 9 for cleaning gases, such as for instance fluegases, in which use is made of panels 1 as according to FIGS. 1 and 2.Device 9 comprises a housing 18 in which panels 1 are accommodatedvertically and at a mutual distance. Device 9 comprises a water feed 15which supplies water to water feed conduit 12 connected via connections13 to each water feed 3 of panels 1, which water feed conduit 12supplies water at low pressure to feeds 3 during operation. As describedabove, this water is pressed upward into each cavity 7, from where thewater flows downward through openings 4 over outer surfaces 5 (see FIGS.1, 2), these outer surfaces 5 being in this application the surfaces ofpanels 1 directed toward the gases that are flowing by. Device 9 alsocomprises a receptacle 17 for receiving the water running off panels 1and a discharge 16 connected to receptacle 17 for discharging the water.

Device 9 also comprises corona wires 11 which are under high voltageduring operation (in the order of magnitude of 50 kV) relative to panels1, this voltage being applied by a voltage source (not shown) connectedbetween panels 1 and corona wires 11.

Device 9 is applied in the following manner in order to clean gases. Thegases for cleaning are guided in direction 10 between panels 1 disposedvertically at a mutual distance. As the gases pass between panels 1 thegases are exposed to corona discharge by means of corona wires 11,whereby impurities present in the gas ionize and are therefore attractedby the panels. The impurities are hereby collected on the surfaces 5 ofpanels 1 directed toward the gases, where the impurities are entrainedto the underside of panel 1 with the liquid flowing downward out ofopenings 4 over the surfaces 5 of panel 1 directed toward the gases. Theliquid with the impurities is then received in receptacle 17 anddischarged via discharge 16. The cleaned gases, thus with impuritiesremoved, leave device 9 in direction 19. Such a method is preferablyperformed continuously.

Openings 4 are preferably sufficiently large that they will not becomeblocked by possible impurities present in the water in cavity 7. Ifblockage of an opening 4 has however occurred, a panel 1 can be cleanedin simple manner by placing cavity 7 into medium-throughflow connectionwith the environment via feed 3 for the purpose of discharging theliquid present in cavity 7 from cavity 7 via feed 3 such that anunderpressure is created in cavity 7. Owing to the thus createdunderpressure air will be suctioned into cavity 7 through openings 4,whereby the impurities are easily removed from openings 4. It is notedthat the panel can be provided for this purpose with a discharge.

FIGS. 4 and 5 show an embodiment, in which a series of perforations orthrough-holes 4 are arranged close to and extending along the uppersealed edge 22 of panel 21, in accordance with the arrangement shown inFIG. 1.

The diamond pattern of welding zones 23, over which the two plates arefixed to each other, defines the cavity 24 between them, as shown inFIG. 5. The regular, though non-flat shape of the outer surfaces ofpanel 21 has the important effect, that the water 8 flowing out of theopenings 4 in downward direction over the outer surfaces of the panels,does not have a tendency to gradually concentrate in the middle zone ofpanel 21, which unwanted phenomenon may occur in case of smooth and flatsurfaces, but ensures that the flow is evenly distributed oversubstantially the whole respective outer surface. For this reason, theuse of a pillow plate in accord with the FIGS. 4 and 5 embodiment ispreferred.

The holes 4 may have any suitable dimension and shape. It is to beexpected that a simple round shape is perfectly effective. Such a shapecan be readily be arranged by drilling or laser cutting. The holes mayhave any practical diameter, e.g. in the order of magnitude of 2-6 mm.

The invention is not limited to the shown embodiment, but also extendsto other variants falling within the scope of the appended claims.

1. A panel, comprising: two plates of substantially equal dimensionspositioned on each other; which plates are connected medium-tightly toeach other along their peripheral zones; which plates enclose a cavity;a feed for feeding a liquid, in particular water, into the cavity; andopenings close to and along one peripheral edge of the panel for flow ofthe liquid out of the cavity during operation such that during operationthe openings are situated close to the upper peripheral edge of thepanel, wherein the liquid flows downward over at least one outer surfaceof the panel.
 2. The panel as claimed in claim 1, wherein the openingsare arranged in at least one of the two plates.
 3. The panel as claimedin claim 1, wherein the openings are situated at a constant mutualdistance from each other, and wherein the distance between an openingand the nearby peripheral edge of the panel is the same for eachopening.
 4. The panel as claimed in claim 1, wherein the openings aresufficiently large to allow at least substantially laminar flow of theliquid out of the openings during operation.
 5. The panel as claimed inclaim 1, wherein the feed is situated close to a second peripheral edgeof the panel, which second peripheral edge extends opposite theperipheral edge close to which the openings are arranged.
 6. A method ofmanufacturing a panel, which method comprises the following steps, to beperformed in suitable sequence, of: (a) positioning two plates ofsubstantially equal dimensions relative to each other; (b) connectingthe two plates medium-tightly to each other along their peripheralzones; (c) arranging a feed in the panel; (d) feeding an inflatingmedium under pressure via the feed such that the two plates, undergoingplastic deformation, move apart in the area between the peripheralseams, thereby creating a panel with a cavity; and (e) arrangingopenings close to and along one peripheral edge of the panel for flow ofa liquid out of the cavity during operation.
 7. The method as claimed inclaim 6, further comprising the step of locally connecting the twoplates to each other prior to step (d) by means of a pattern of weldedzones distributed regularly over the surface, wherein in step (d) thetwo plates, undergoing plastic deformation, move apart in areas betweenthe welded zones.
 8. The method as claimed in claim 6, furthercomprising the step of exposing the two plates to a corona treatment,wherein grease present on the plates degrades, whereby the liquidflowing through the openings during operation forms a thin film on atleast one outer surface of the panel.
 9. A method for cleaning a panelas claimed in claim 1, comprising placing the cavity intomedium-throughflow connection with the environment via the feed for thepurpose of discharging the liquid present in the cavity from the cavityvia the feed such that an underpressure is created in the cavity.
 10. Adevice for cleaning gases, comprising at least two panels as claimed inclaim 1 disposed vertically at a mutual distance; these panels beingdisposed such that the openings are situated close to the upperperipheral edge of the panel; at least one corona electrode arrangedbetween adjacent panels for the purpose of ionizing impurities presentin the gases; a voltage source connected between the or each coronaelectrode and each panel such that a voltage is applied between the oreach corona electrode and each panel, whereby impurities present in thegases are ionized; which ionized impurities collect during operation onthe surfaces of the panels directed toward the gases; which collectedimpurities are removed from the panels during operation by means of theliquid which flows downward out of the openings over the surfaces of thepanel directed toward the gases; and a discharge for discharging theliquid with the collected impurities.
 11. The device for cleaning gasesas claimed in claim 10, further comprising receiving means for receivingthe liquid with the collected impurities, these receiving means beingconnected to the discharge.
 12. The device for cleaning gases as claimedin claim 10, further comprising a housing in which at least the panelsand the or each corona electrode are accommodated.
 13. A method forcleaning gases, the method comprising the following steps, to beperformed in suitable sequence, of: (a) guiding the gases for cleaningbetween at least two panels according to claim 1 disposed vertically ata mutual distance, wherein the panels are disposed such that theopenings are situated close to the upper peripheral edge of the panel;(b) exposing the gases for cleaning to corona discharge for the purposeof ionizing impurities present in the gases; (c) collecting theimpurities on the surfaces of the panels directed toward the gases; (d)feeding a liquid via the feed into the cavity for the purpose of causingthe liquid to flow out of the cavity through the openings; (e) removingthe collected impurities from the panels by means of the liquid whichflows downward through the openings over the surfaces of the paneldirected toward the gases; and (f) discharging the liquid with thecollected impurities.
 14. The method as claimed in claim 13, wherein theliquid is fed into the cavity under low pressure via the feed in step(d), wherein the feed is situated close to the lower peripheral edge ofthe panel, and wherein the method further comprises the step of (g)pressing the liquid upward in the direction of the openings for thepurpose of causing the liquid to flow out of the cavity through theopenings.